This document summarizes SSL/TLS, including what it is, how it works, and where it fits. SSL/TLS uses cryptography like key exchange, privacy, and message integrity to encrypt network connections above the transport layer, securing protocols like HTTP, SMTP, and POP3. The handshake protocol is described, including the client hello, server hello, and key exchange steps. Applications that use SSL/TLS are discussed, such as HTTPS for secure web browsing and mail protocols like SSMTP and SPOP3.

1. Introduction
SSL/TLS
Nguyen Ngo, Ninh Khong

2. Agenda
Introduction
 Background
• What ‘s SSL/TLS?
• Cryptography Methods.
• Where SSL/TLS Fit?
• SSL Architecture
HandShake Protocol
• Client Hello.
• Server Hello
• Client Exchange
Applications
 Web and Mail
 Other

3. INTRODUCTION

4. Background

5. What ‘s SSL/TLS?
Transport Layer Security (TLS) and Its
predecessor, Secure Sockets Layer (SSL),
are cryptographic protocols that provide
communication security over the Internet.
TLS and SSL encrypt the segments of
network connections above the
Transport Layer.

6. Cryptography Methods
• Key Exchange: Using Assymmetric Cryptography.
• Privacy: Using Symmetric Cryptography.
• Message Integrity: Using Message Authentication
Codes (MAC).

7. Where SSL/TLS Fit?
HTTP SMTP POP3 HTTPS SSMTP SPOP3
80 25 110 443 465 995
Secure Sockets Layer
Transport
Network
Link

8. SSL Architecture

9. HandShake
Protocol

10. Handshake Protocol
1 ClientHello
1
ServerHello 2
2
Client Certificate 3
Server
3
CertificateRequest 4
4
“ServerHelloDone” 5
5
6 Certificate
6
7 ClientKeyExchange
7
8 CertificateVerify
8
9 [ChangeCipherSpec]
9
10 Finished
10
[ChangeCipherSpec] 11
11
Finished 12
12

11. Client Hello (RFC)
struct {
TimeStamptimestamp;
ProtocolVersion client_version;
Random random;
SessionID session_id;
CipherSuite cipher_suites;
CompressionMethod compression_methods;
} ClientHello

12. Server Hello
Client 1 C, Versionc, suitec, Nc
1
Server
Versions, suites, Ns, 2
2
sigca(S,Ks), 3
3
“ ServerHelloDone” 4
4

13. Client Key Exchange
Client 1 C, Versionc, suitec, Nc
1
Server
Versions, suites, Ns, 2
2
sigca(S,Ks), 3
3
“ServerHelloDone” 4
4
5 {Secretc}Ks
5

14. Applications

15. Web and Mail
• HTTPS
• Secure Mail
• SSMTP
• SPOP3

16. Others
• sTelnet
• sTunnel
• OpenSSH
• SSLProxy
• sFTP

17. THANK YOU